Safety device for elevators



Jan. 5, 1932. N. o. LINDsTRoM SAFETY DEVICE FOR ELEvAToRs Filed Deo. 12, 1928 2 Sheets-Sheet INVENTOR M- MM ATTORNEY Jan. 5, 1932. N. o. LINDSTROM SAFETY DEVICE FOR ELEvAToRs Filed'nec. 12, 192s 2 Sheets-Sheet 2 Patented Jan. 5, 1932 iJiTEDf STATES PATENT OFFICE NILS O. LINDSTROM, OF NUTLEY, NEW JERSEY, SSIG-NOR TO BLSEE-ELEVATOR- COM- PANY, ING., A CORPORATION yOF l:DELAWAREV SAFETY DEVICE FOR ELnvAToRs Application led December 12, 1928. Serial 110.3254421.`

My invention relates to elevators and more particularly to safety devices for bringing an elevator car to astop upon failure ofits supportingV means. In devices of this character it is highly desirable that the car be brought to alstop as speedily as possible so that it will have little time within which to gain momentum, and the stoppingmay therefore be effected easily and without shock to the car or its occupants. i

f In such devices it is customary to s iiect the stopping by meansy of gripping jaws which are caused to grip the guide rails on each side of the shaft. One of the most desirable means for operating the gripping jaws consists ofapair of oppositely disposed longitudinally movable rods which carry at their outer ends wedges for spreading the opposing arms of the jaws, such' rods being operated by means of screw threads formedthereon and engaged by threaded members which are caused to rotate by means of a drum the exterior surface of which receives the safety cable which may be brought into operation in any well known manner. Y v

In my pend'ng application, Serial No. 107,900, filed May 10, 1926, which has matured into Patent No. 1,700,137, issued J anu- V ary 29, 1929, I have disclosed and claimed an apparatus of this type of a particularly desirable form in that the longitudinally movable rods are yieldable after the resistance offered by the gripping means reaches a predetermined value, such yielding beingopposed by a spring which offers a resistance to the movement ofthe nut by which the longitudinally movable rod is operated.

In safety devices ofthe character described it is highly desirable that the longitudinal rods which carry the wedges for engaging the arms of the gripping jaws be given a very rapid initial movement so that they will' cause the jaws to contact with the guide rails as soon as possible, and thereafter the movement of the rods may be at a reduced speed since the distance which will then be traversed by the rods in order to effect the complete stopping of the car is slight. 'i

The present invention has for its object the provision of improved means for causing dinally movable rods.

rapid initial movement of said rods followed by movement at a slower rate, such speed change being brought about by mechanism or gearing between the usualdrum upon which the safety cable is wound and the longitu- Theinvention comprises broadly the improved gearing and also thecombination of'such gearing with means for permitting the yieldingof the longitudinallymovable rods after the resistanceoffered by the grippingmeans reaches a predetermined value. My invention also comprises such improved details of construction .ina devic-eof the character mentioned as will be hereafter pointed outand claimed. c

Reference is hereby made tothe accompanying drawings of which: Y

F igll isa plan view of an elevator safety device constructed in accordance with my invention;

Fig. 2'is a central vertical section of the same; i.

F- g. 3 is a plan view of a modification;

Fig. 4 is a central vertical section of the same,and l f Fig. 5 yis a section on line 5 5 of Figs. l and 3. l f 1 In the device shown in Figs. 1 and 2 the movable parts A`are supported by a frame carried by the elevator car and mounted. preferably below Vthe floor thereof. This frame comprises longitudinal members 1, 1` united soV by transverse members 2, 3 and 4; vThe grippingajaws shown are ofv the usual type consisting of oppositely Y. disposed members 5, 5 pivoted on a vertical pin 6 andthe inner ends of themembers 5 are'V provided vwith rollers 7 mounted on vertical pins 8.

rIhe means for operating sist of a pair of oppositely disposedand oppositely Ythreaded. longitudinally Vmovable rods 9, 9. vMeans are provided for preventing rotation of said rods, and as shown comprise horizontal guides 10 secured to the members 1 which are engaged within notches 10"l in the ends of the transverse `arms 11 of the members 12. 'Ihemembers 12 are secured to the rods 9 by any suitable means as, for example, the set screws 11a. The outer end of'each of the lrods 9 is provided with a the said jaws coni wedge 15 for cooperation with the rollers 7 of the jaws 5, said wedge being provided with a socket 15a which receives the reduced end of the rod 9 and is united thereto by a pin 14. There is a pin 16 threaded in the end of the wedge 15 which normally occupies a position, as shown, betweenthe two rollers 7, its purpose being to properly position the wedge 15 for quick action to c 5 to grip the Vguide rail.

The inner ends of the rods 9 are provided with screw threads 17 and said rods at their inner extremities are provided with bolts 19 whose shanls 18 are threaded therein and secured by lock-nuts 20. These bolts are adjustable longitudinally with respect to the rods 9 and serve to determine the innermost or off position of said rods.

Upon each of the rods 9 is mounted a sleeve 21 which is provided with an internal thread 22 in engagement with the thread 17 of the rod 9. Upon the exterior surface of the sleeve 21 is formed a screw thread 23 the pitch of which is considerably greater than that of the threads 17 and 22 and upon such portion of the sleeve and in engagement with the thread thereof is an internally threaded nut 24. This nut is circular in outline to conform tothe inner surface of the safety cable drum 25, notches (not shown) being formed in its periphery for engagement with horizontal ribs 26 integral with said drum. Such'ribs serve as driving means for the nuts 24, ant also as guides for permittingmovement thereof in a horizontal direction; Each of the nuts 24 isprovided with an annular groove or recess 27. These grooves are directed in-. wardly and a spiral spring 28 is mounted with its ends in the opposing grooves so as to oppose by its resilient action movement of the two nuts toward Aeach. other. The inner ends of the sleeves 21 are threaded as shown` and upon. said threaded ends Vare mounted collars 29, the purpose of which will be referred to later.

Upon the outer end or extremity of each sleeve 21 is mounted a friction vdevice for opposing the rotation thereof. Such device as shown-consists of a clamp formed of upper and lower plates 31 and 32 respectively. The middle portions of these plates are curved to fit the exterior'surface of the. sleeve 21 and are held in frictional contact therewith by threaded bolts 33 which draw the ends of the plates toward each other. By means of nuts 34, washers 35 and spiral springs 36. the amount of friction developed between plates 31 and 32 and the sleeve 21 may be adjusted or regulated to any desired value. ri`he .ends of theplates 31 and 32 are separated by a suliicient space to receive the guides 10 without frictional engagement therewith. The clamping plates 31 and 32 are retained against displacement longitudinally of the sleeve 21 by a collar 37 which bears against a shoulder ause the` jaws c tegral worm gear 41 and an interior bearino surface 42.' rl`his surface receives its support from the bearing ring 43 of the support 4 and the end plate 40 receives similar support from the ring 43 of the support 3. The support 4 is hollow and encloses sain worm Vgear 41 and there is a vertical hand shaft 44 the upper end of which entends through the floor of the car. The lower end of the said shaft is mounted in a step bearing 45 integral with the support 4 and a worm 46 formed on the shaft 44 engages the worm gear 41.

The operation of the device is as follows: As soon as the elevator begins to drop, or as soon as in dropping it attains a given speed (according to the type o-f safety cable which is used) the safety cable begins to unwind and causes the drum 25 to rotate. Such rotation by reason of engagement of guides 26 with nuts 24 causes the rotation of the later and such rotation causes a very rapid movement in an outward direction of the sleeves 21 due to the engagement of the internal thread of the nut 24 with the thread 23 of said sleeve, and the fact that the sleeve is held against rotation at this time by the frictionclamp comprising` plates 31 and 32. This outward movement of the sleeve 21 to` gether with the friction clamp continues until the collar 29 abr-.ts against the nut 24. Such engagement prevents any further outward movement of the sleeve and by reason of the ambing action of the collar 29 against the nut which loclfs the nut and sleeve together causes the sleeve to be rotated with the nut overcoming the resistance oered by the engagement of the friction plates 31 and 32 with the surface ofthe sleeve.

By reason of the rotation of the sleeve 21 the outward movement of the rod 9 is continued although at aslower rate'of speed by reason` of the engagement of the vinternal thread 22 of the sleeve with the thread 17.

As soon as the resistance oi'i'ered by the gripping means by reason of the engagement of the jaws with the guide rails reaches a predetermined value the rotation of the nuts 24 instead of causing further outward movement of the rods 9, causes inward movement of the nuts 24, since the resistance offered by the spring 28 is less than that of the jaws 5 with respect to the wedge 15 carried at the extremity of the rod 9. rlhis cushioning effect is very desirable and the means by which it is obtained is fully disclosed and broadly claimed in the aforesaid Patent No. 1,700 137.

By reason of the friction developed between the gripping aws and the guide rails the car is speedily brought to aV complete and b-y reason of the engagement of worm 46 and worm gear 4l will rotate thedrum 25 in a reverse direction, thereby causing first the nuts 24 to return to the position shown and then the rods 9 to be moved inward until the heads of the adjusting bolts. 19 Contact with eachother as shown.V y Y Further rotation-of the drum 25 vthereupon causes the sleeves 2l, to be moved upon said'rods into the position shown in the drawings which represent the normal position of the apparatus during the operation of the' car. Y y

Referring to Figs. 3 and 4, the structure shown is the same as that of Figs. l and 2 with the exception of the means for frictionally opposing the rotation ofthe sleeve In the modified structure the sleeve 2l is provided at its outer extremity with a conical'friction surface 47. The member 13 is slidably mounted on the rod 9 and is provided with a conical friction surface 48 which engages with the surface 47 of the sleeve 2l, being` held in Contact therewith by a coil spring 49 which surrounds the rod 9. @ne end of this spring bea-rs against the member i3, and the other against an adjustable collar 50 which is internally threaded and mounted upon the threaded portion 5l of the rod 9. This collar after being properly adjusted is secured in the desired position by the pin Q-which passes through the collar and rod.

The mode of operation of this structure is similar to that of the device of Figs'. l and 2 but differs therefrom in that as soon as the outward movement of sleeve 2l causes collar Q9 to jam against nut 24 and thereby lock the sleeve and nut together, the outward movement of rod 9 due to rotation of sleeveA 2l upon said rod immediately separates the friction members 47 and 48, since the latter moves outward away from the former.

Having now described my invention, what l claim is:

l. ln an elevator safety device, the combination of guide rail gripping means, a longitudinally movable threaded rod for actuating said gripping means, means for holding said rod against rotation, a rotatable member engaging the thread of said rod for causing longitudinal movement of said rod, means for rotating said rotatable member, and friction means for opposing the rotation'of said rotatable member.

2. ln an elevator safety device, a revolvable drum, guide rail gripping means, a longitudinally movable rod, and mechanism for gearing said drum to said rod including a friction device and means for overcoming the resistance of said friction device.`

3. `ln an elevator safety device,`a revolvable drum, guide rail grippingmeans, a longitudinally movable rod, and mechanism for gearing said drum to said rod including av friction device and means for overcoming the resistance of said 4friction device upon the movement of said rod through a predetermined distance.

4.*ln an elevator safety device, the combination of guide rail gripping means, a longi- Y tudinally movable threaded rod for actuating said gripping means, means for holding said rod against rotation, a rotatable member engaging the thread of saidrod for causing longitudinal movement of said rod, means for rotating said rotatable member, and friction means to hold said member againstrotation, said rotatable member having an additional thread of greater pitcthan the other thread, and rotatable driving means in engagement therewith. j

5. In an elevator safety device, a revolvable drum, guide rail gripping means, a longitudinallymovable rod, means for holding said rod against rotation, and mechanism including a friction device for gearing the drum to the rod to cause the form-er tol actuate the latter first at high' speed and then at a lower speed. j

6. ln an elevator safety device, revolvable' drum, guide rail gripping means, a longitudinally movable rod, means for holding` said rod against rotation, and mechanism including a friction device and a member having threads of different pitch for gearing the drum' to the rod to cause the former-to actuate the` latter first at high speed and then at a lower speed.

7. In au elevator safety device, a `revolvable drum, guide rail gripping means, a longitudinally movable rod, means for holding said rod against rotation, mechanism comprising afriction device for gearing the drum to the rod to cause the former to act-nate the latter tudinally movable rod, means for holding said rod against rotation, mechanism comprising a friction device for gearing the drum to the rod to cause the former to actuate the'latter first at high speed and then at a lower speed, and means for adjusting the strength of said frictiondevice. y

9. ln an. elevator safety device, a revolvable drum, guide rail grippi'ig means,`a longitudinally movable threaded rod, means Vfor holding said rod against rotation, mechanism for gearing the drum to the rod to cause the former to actuate the latter, said mechanism including a nut'driven by the drum, a sleeve having a thread engaging said nut and an additional thread engaging the thread of said rod, and friction means for holding said sleeve against rotation on said rod.

V l0. ln an elevator safety device, a revolvn, 1guide rail gripping means, a naliy movable threaded rod, means d rod against rotation, mechanism for gearing the drum to the rod to cause the former to actuate the latter, said mechanism including` a nut driven by the drum, a sleeve having a thread engaging said nut and an additional thread engaging the thread of said rod, friction mea-ns for holding said sleeve against rotation on said rod, and means whereby longitudinal movement of the sleeve for a predetermined distance loclis it to said nut.

ll. ln an elevator safety device, a revolvable drum, guide rail gripping means, a lonfitudinally movable threaded rod, means for iolding said rod against rotation, mechanism or gearing the drinn to the rod to cause the ormer to actuate the latter, said mechanism including a nut driven by the drum, a sleeve havi a thread engaging said nut and an addi ional thread engaging the thread of said red, means for holding said sleeve against rotation on said rod, and means wherebyT longitudinal movement of the sleeve for a predetermined distance causes the sleeve to jam against said nut and prevent relative rotation of sleeve and nut.v

l2. ln an elevator safety device, the combination of a threaded longitudinally movable rod, a sleeve having an internal thread engaging the thread of said rod and an additional thread of greater pitch, a friction surface on said sleeve, a member having a friction surface bearing thereon a spring for pressing .said friction surfaces together, and means for varying the pressure of said spring.

13. ln an elevator safety device, the com'- bination of a threaded longitudinally movable rod, a sleeve having a thread engaging the thread of said rod and an additional thread of greater pitch, a nut engagingk said additional thread, means for driving said nut. to traverse said sleeve, and means on the sleeve adapted by such movement of the sleeve to engage said nut to lock said nut and sleeve together.

le. In an elevator safety device, the `combination of guide rail gripping means, a longitudinally movable threaded rod for actuating said gripping means, means for holding .said rod against rotation, means engaging the thread of said rod for causing longitudinal movement of the rod rst at a high speed and thereafter at a lower speed, and spring means for permitting longitudinal yielding of said rod only after the resistance offered by the gripping means reaches a predetermined value.

l5. In an elevator safety dev-ice, they combination of-guide rail grippingI means, alo11- gitudinally movable threaded rod for actuating said gripping means, means for holding said rod against rotation, a sleeve engaging the thread of said rod for causing longitudinal movement of the rod first at a high .speed and thereafter at a lower speed, a nut for actuating said sleeve and spring means engaging said nut for permitting longitudinal yielding of said rod only after the resistance offered by the gripping means reaches a predetermined value.

16. ln an elevator safety device, the combination of a drum, a sleeve and longitudinally movable rods actuated thereby, of longitudinal guides and a friction device engaging said guides and applied to said sleeve to opp-ose rotation thereof.

17. ln an elevator' safety device, the combination of a drum, a sleeve and longitudinally movable rods actuated thereby, of longitudinal guides and a pair of friction plates engaging said guides and clamped upon said sleeve to oppose rotation thereof.

ln Witness whereof, l hereunto subscribe my signature.

NILS O. LNDSTROM. 

